To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post Long Term Evolution (LTE) System’. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 28 GHz or 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.In the 5G system, Hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
A communication system consisting of a cascade chain topology may include a Digital Unit (DU) and a plurality of Radio Units (RUs). A RU located in a specific hop generates uplink data by adding data received from its antenna and data received from a RU of a lower-level hop. In addition, the uplink data is transmitted to a RU of a higher-level hop or the DU. Herein, when the uplink data is transmitted to the higher-level hop or the DU, data received from the RU of the lower-level hop and data received from its antenna are accumulated, thereby gradually increasing an amount of data. The number of transmittable valid bits is limited in a transmission line due to physical or economic constraints. Therefore, in a specific hop, the number of valid bits of the accumulated data may exceed the number of bits that can be transmitted on the transmission line. In this case, data may be transmitted with distortion when the uplink data is transmitted to the RU of the higher-level hop or the DU. As a result, distortion of an uplink signal to be transmitted may increase in proportion to an increase in the number of RUs in a communication system coupled with a cascade chain.
To solve this problem, each RU transmits data to a higher-level entity by decreasing an amount of received data, so as not to exceed the number of bits that can be transmitted on the transmission line. In this case, since uplink data is accumulated and transmitted when the hop of the RU is located close to the DU, a decrement level of the uplink data changes depending on the location of the RU. Accordingly, there is a problem in that transmission cannot be achieved while maintaining the same decrement amount for each RU having a different hop location.